A laminate type energy device, an electric double layered capacitor and the like are known as a laminate type energy device. For example, a laminate type energy device includes a laminated body having laminated electrodes and separator and impregnated with an electrolyte, a laminate sheet (an aluminum laminate package) encapsulating the laminated body, and tab electrodes led from the laminated body out of the laminate sheet to allow the laminated body to be electrically connected to the outside.
An electric double layered capacitor has an advantage of long lifetime because it has low internal resistance. In addition, the electric double layered capacitor is capable of being charged/discharged in a short time and has low deterioration caused by charging/discharging.
There have been proposed various techniques for implementing the electric double layer capacitor.
As an example, a technique for providing a high-capacity thin capacitor is disclosed in which a required number of collector electrodes, each having polarizing electrode layers formed on a surface of a band-like metal foil and a required number of band-like separators are alternately stacked, the stack is folded, the separator is impregnated with an electrolyte to form an electric double layer capacitor element, the electric double layer capacitor element is encapsulated into a package, lead tabs made of thin metal are mechanically or electrically coupled to each collector electrode, and these lead tabs are drawn out via an encapsulation hole of the package.
However, in such a laminate type energy device, lead-out electrodes and tab electrodes constituting a collector electrode are welded to form positive and negative electrodes. In addition, encapsulation material (sealant) made of, for example, CPP (Cast PolyPropylene) a kind of thermoplastic resin, is wound on ends of the tab electrodes. In addition, when a sheathing laminate sheet coated with the CPP is used to encapsulate the entire storage device by heating an edge of the sheathing laminate sheet, the encapsulation material is melted together and the entire storage device is encapsulated.
However, in the above structure, since a step in a welding portion of the lead-out electrode and the tab electrodes constituting the collector electrode is only insulated by the CPP coated on the inner side of the sheathing laminate sheet, there is a high possibility of a short-circuit between the tab electrodes and the sheathing laminate sheet.
In addition, in the above structure, there is a possibility that a gap is produced between the tab electrodes and the sheathing laminate sheet, which may result in low airtightness and leakage of the electrolyte.